Ever17 is an amazing visual novel and the only VN where I could see that couldn't be a book or a manga or anime and also proved that the last route can save a game.
Fate/Stay Night is a fighting visual novel that feels like an RPG and a novel at the same time, I really love this one.
Tsukihime is great but since this is an amateur/doujin work in Nasu's time I can understand why some people can't like it until they got away from Arcuied's route and Ciel.
Narcissu is a great Visual novel that made me cry

The later series seems to disappoint me specifically the 3rd one but I have yet to wait for those to be translated in english.
Togainu No Chi is...<3
Higurashi and Umineko no Naku Koro Ni is \m/
Very amazing. The latter one is 10034243241234124x better.
Insani has a lot of them too specially the festival translated ones seem pretty good.
Also Katawa Shoujo. Very good for a non Japanese Amateur group and actually very likeable.
Saya No Uta, a short visual novel and direct to the point with only 3 choices in the whole game and damn that game almost made me cry ;_;
The Noose is also pretty good from dejavu. It's not as highly graphical and more of a kinetic novel but it works great.